Revolutionizing Industrial Piping - SS316 Slip-On Flange

A 3-inch SS316 slip-on flange rated 150 lb RF to ASME B16.5 is the economical stainless joint for low-to-moderate pressure lines: it slides over the pipe and is fillet welded at the hub, so fit-up is fast and forgiving. On the face it seats with our flange gaskets.

What the SS316 Slip-On Flange Is

The slip-on (SO) flange has a bore slightly larger than the pipe OD, so it slides on before the weld. A fillet weld inside and out joins it to the pipe, and the raised face (RF) gives the gasket a defined sealing band. ASME B16.5 sets the dimensions, bolt pattern and pressure-temperature ratings; the 3-inch 150 lb size is among the most common in utility and process piping.

• Bore slightly larger than the pipe OD — slides on easily for quick fit-up.
• Fillet weld inside and out — no full-penetration weld required.
• 150 lb RF rating — the working pressure limit at a given temperature per B16.5.
• SS316 (316) body — molybdenum-bearing stainless for chloride resistance.

Why SS316 and Slip-On

SS316 resists chloride pitting and crevice corrosion better than 304, which matters in coastal, washdown and process-chemical service. The slip-on form costs less than a weld neck and is easier to align. It is not the choice for cyclic or high-temperature lines, where the butt weld and tapered hub of a weld neck handle stress better.

Key Benefits

• Fast, forgiving installation — slides on and tack welds before final welding.
• Lower cost than weld-neck flanges at the same pressure class.
• 316 stainless resists rust, pitting and many process chemicals.
• Standard B16.5 dimensions — interchangeable with other compliant flanges.

Where They Are Used

Slip-on flanges serve water, steam, oil, air and mild chemical lines in oil and gas, petrochemical, power generation, food and beverage, and general plant piping. The 3-inch size is common on utility headers, skids and equipment nozzles where cost and easy maintenance matter.

In the Joint

The flange slides over the pipe and is fillet welded at the hub; the gasket between the faces seals the joint while the bolts set the load. Match the gasket to the media, and keep the pipe flanges torqued evenly in a cross pattern.

Installation and Care

Cut the pipe square, slide the flange on, and align the bolt holes before tacking. Fillet weld inside and out with a qualified procedure, then let it cool before final torque. Do not use a slip-on where the design calls for a weld neck in high-temperature or cyclic service. Inspect at turnaround for weld cracking and face damage, and replace the gasket whenever the joint is opened.

Frequently Asked Questions

Slip-on or weld neck — how do I choose?

Use a slip-on for low-to-moderate pressure, easy install and cost savings. Choose a weld neck for high temperature, cyclic or severe service where the butt weld and tapered hub give better stress performance.

What does 150 lb RF mean?

150 lb is the ASME B16.5 pressure class, and RF means raised face — the gasket sits on a raised ring that concentrates the bolt load.

Does SS316 need a special gasket?

Pair it with a gasket rated for the media and temperature; for chloride or steam service choose graphite- or PTFE-based sheets and torque evenly.